Instruments such as guitars, violins, cellos, banjos and mandolins produce sound by way of vibrating strings that are fixed at two end points. The strings are held under constant tension and the sound produced by each string is varied by selectively shortening or lengthening the strings by pressing the strings against a fingerboard mounted atop an elongated neck attached to the body of the instrument. The neck on a typical guitar is divided into portions called frets which represent various notes on the chromatic scale. Other stringed instruments such as violins, violas, cellos and double basses do not have frets and therefore an infinite number of tonal frequencies may be produced. A user (i.e. a player) uses the instrument to produce sounds of various frequencies by applying pressure to frets or positions on the instrument's fingerboard and causing the strings to vibrate by strumming, plucking or bowing the strings. The sound of the vibrating strings can be amplified by constructing the instrument's body from a resonating material such as wood. In addition, pick-ups can be used to convert the string vibration into electrical signals which can then be sent to a speaker for amplification.
In order to produce sound, the strings of such instruments must be stretched and kept under high tension. For example, once properly tuned, the strings of a six-string acoustic guitar can require a total tension of approximately 200 pounds. The body of the guitar and the guitar neck must therefore be strong enough to withstanding such high tension without deforming or causing separation of the neck and body. In addition to withstanding high string tensions, the neck must be joined to the body in such a way as to maintain strength, rigidity and playability of the instrument.
Various methods exist for attaching the necks of instruments such as guitars, violins, banjos and mandolins to the body of the instrument. In the case of solid-body electric guitars such as the Fender® Stratocaster, the neck is attached to the upper part of the body using screws. This method generally requires the use of four screws to mount the lower portion of the neck to the upper portion of the guitar body. While this “bolt-on” method provides a great deal of strength, the guitar's playability is hindered due to a rectangular heel formed where the neck is bolted to the body. The heel prevents a player's hand from easily accessing higher positions on the fingerboard when the guitar is played in the normal or convention playing position due to the heel's size and positioning relative to the end of the neck.
The normal playing position can vary depending on the type of acoustic or semi-acoustic stringed instrument. In the case of instruments such as guitars, bass guitars, mandolins and ukuleles, the instrument's body is generally situated near the mid-section of the player's body. The instrument can be played while the user is in the seated position or the instrument can played while the user is standing by means of a strap or similar mechanism that suspends the instrument from the user's shoulder. Depending on user preference, the angle of the neck may be varied about the horizontal axis. The player uses one hand to strum or pluck the instrument's strings while the other hand varies the string length using the fingerboard. In the case of instruments such as violins and violas, the instrument's body is generally supported between the user's shoulder and chin with the instrument's neck generally kept parallel to the horizontal axis. The player uses a bow in one hand to make the strings vibrate and uses the other hand to vary the string length on the fingerboard. In the case of instruments such as cellos and upright basses, the instrument is generally held in an upright position perpendicular to the horizontal axis. A user may play these instruments in the seated or standing position. The player then uses one hand to either pluck or bow the strings and uses the other hand to vary the string length on the fingerboard.
Many acoustic stringed instruments also utilize a “bolt-on” method to attach the neck to the body. For example, the neck of an acoustic guitar is constructed with a heel plate (or foot) that extends perpendicularly from the base of the neck. Two holes are drilled in the face of the heel plate and screws are used to affix the face of the heel plate to a block located in the upper portion of the instrument's body. In an acoustic guitar, the heel plate is generally located near the 12th fret. As in the case of a bolt-on neck in the solid-body electric guitar, the heel plate in an acoustic guitar neck prevents a player's hand from accessing frets above the 12th fret and therefore results in significant playability issues when the acoustic guitar is played in the normal position.
Some acoustic and hollow-body electric guitars and many bowed instruments (such as violins, violas and cellos) use dovetail or mortise joints to attach the neck to the body of the instrument. This configuration is very similar to the bolt-on acoustic guitar neck in that it uses a heel plate (or foot) which extends perpendicularly from the base of the neck. However, the face of the heel plate contains either a tapered dovetail joint or straight mortise joint which is glued to a corresponding joint on the upper part of the instrument's body. As in the case of a bolt-on neck, a neck affixed to the instrument body using a dovetail joint has the same playability issues because of the heel geometry. The heel prevents a player's hand from accessing higher frets on the fingerboard when the instrument is played in the normal position.
Finally, many classical and flamenco-style guitars use a flat heel plate to attach the neck to the body of the instrument. The heel plate is comprised of a flat surface that is glued directly to a flat plate on the upper body of the instrument. Classical and flamenco-style guitars still have playability issues because of the heel located at the base of the neck which prevents a player's hand from reaching frets above the 14th fret when the instrument is played in the normal position.
The playability and fret-access problems in solid body electric guitars have been overcome using a neck-through-body approach similar to that described in U.S. Pat. No. 6,888,054 issued to Minakuchi. The neck in a neck-through-body guitar has an additional portion that extends integrally from the base of the neck. The extended portion of the neck is then mounted into a rectangular engagement hollow or channel cut directly into the back of the body of the guitar. In this structure, the neck extends through the entire length of the body thus removing the need for a heel at the base of the neck. A smoothly curved surface or carve-out can be formed in the area where the base of the neck meets the upper part of the guitar body. This carve-out provides the user with greater access to upper frets on the fingerboard when the guitar is played in the normal position.
However, the neck-through-body structure common to many solid body electric guitars is not suitable for use on acoustic or semi-acoustic instruments. A primary disadvantage of using a neck-through structure in an acoustic or semi-acoustic instrument is the fact that having a solid neck extend through the entire body would greatly limit the size of the sound box created by the instrument's body. This reduction in the size of the sound box would reduce the resonating capability of the sound box to an unacceptable level. Another problem is that the neck-through structure would not solve the problem of fret access in an acoustic guitar because of the greater body thickness in acoustic instruments. While a neck-through design would potentially eliminate the heel plate of an acoustic stringed instrument, the body shape and thickness would still prevent a player's hand from accessing higher frets when playing the instrument in the normal position. Another reason a neck-through structure is not suitable for use in acoustic and semi-acoustic instruments is because the carve-out feature on many neck-through-body electric guitars could not be replicated in an acoustic or semi-acoustic instrument because of the lack of a solid upper body portion capable of accepting the carve-out
Therefore, a need exists in the art for an acoustic or semi-acoustic instrument having a neck joined to the body in a manner that eliminates the traditional heel obstruction and thereby allows greater ease in accessing higher positions on the fingerboard when the instrument is played in the normal position. In addition, there is a need for a neck-to-body junction which is strong enough to withstand high string tension while maximizing the size of the instrument's sound box.